“He said, ‘Go ahead, I work in the private sector,’” she added. “Then he smacks my ass again.”

The incident was corroborated by a friend of the singer’s who attended the party, Politico reported.

Mr. Lewandowski did not respond to multiple requests for comment prior to Politico publishing its report Friday evening, according to the article. He did not comment publicly on the allegations as of late Saturday morning.

Mr. Lewandowski, 44, served as Mr. Trump’s presidential campaign manager from January 2015 through June 2016. He subsequently formed Lewandowski Strategic Advisors and remains close to the White House.

Ms. Villa made headlines in February after she attended the 2017 Grammy Awards wearing a blue dress decorated with the words “Trump” and “Make America Great Again.” The outfit boosted sales of her 2014 record, “I Make the Static,” and she’s since floated the possibility of running for office.

“Have you looked at Congress lately? In the news, we see that they’re getting nothing done. They are a house of cards that is tumbling. I mean, healthcare reform they couldn’t get done. Immigration they can’t get done. They are not working with the president, which means we need to put new people in, we need to vote fresh blood,” she told Fox News earlier this month.

“I was at the White House the other night. And I got to see the president at the White House Christmas party. Ivanka actually pulled me aside and said, ‘I really want you to run. We need more strong women to back up, you know, what America needs,’” Ms. Villa added. “So it’s looking good. This congressional possibility is looking more and more like a reality. And I’m proud to dive into it.”

Mr. Trump previously praised the singer’s political ambitions from his Twitter account in October.

“Good luck to @Joy_Villa on her decision to enter the wonderful world of politics. She has many fans,” Mr. Trump tweeted.